Drafting machine



V H, LITTLE 5 DRAFTI NG MACHINE Filed Oct. 12;, 1935 6 Sheets-Sheet l INVENT OR.

0mm ES hf 4/7715 ATTORNEYS.

June 27, 1939. c. H. LITTLE DRAFTING MACHINE Filed 001;. 12, 1935 6 Sheets-Sheet 4 III Z IJIZZ mnnnnumuwu nunnuun \.d H {Hm H. Q

Till ll I I l I I I l l I l ll INVENTOR. CHARLES f2 07725 mam ATTORNEYS Patented June 27, 1939- Charles 1:. Little, Cleveland inmto of one-tenth Heights, one, as

Hubbard Littie, Cleveland Heights, Ohio Application October ,12, 1935, Serial No. (4,741

15' Claims.

chines, and particularly to drafting machines of the band type wherein the arm or parallelmotion mechanism consists of a plurality of parallelograms made up of wheels and flexible bands operatively c'onnected together.

An object of the present invention is the provision of a novel drafting machine comprising a light, strong, inexpensive arm or' parallel motion mechanism of the band type that will give a higher degree of stability to the rulers forming part of the protractor assembly than was heretofore obtainable in the art.

Another object of the invention is the provision of a novel drafting machine comprising an arm .or parallel motion mechanism of the band type,

which can be readily assembled and disassembled for the purpose of repairs or replacement, and in which the bands are covered thereby enhancing the appearance of the machine as a whole and protecting both the bands and the operator against injury.

' Another object of the present invention is the provision oi a novel drafting machine comprising a compact, simple and reliable counterpoise for balancing the weight of the arm, protractor assembly, etc., so that the same will remain in any position to which it is moved irrespective of the inclination of the drawing board or table with which the machine is used.

The present invention resides in certain novel details oi construction, combinations and arf Fig. 2 is an enlarged the drafting machine;

rangements of parts, and further objects and advantages thereof will be apparent from the fol' lowing description of the preferred embodiment thereof described with reference to the accompanying drawings forming a part of the specification. in which similar reference characters designate corresponding parts-throughout the several views, and in which:

Fig. l is a plsnview of a drafting machine embodying the present invention;

plan of the anchor end of Fig. 3 is a section on the line 3-4 of Fig. 2; Fig. '4 is a. section on the line 4-4 of Fig. 2; Fig. 5 is a. section on the line 5-5 oi Fig. 4;

' Fig. 6 is a section on the line t--6 of Fig. 1;

Fig. 7 is an enlarged plan of the elbow portion of. the arm of the drafting machine; Fig. 8 is a section on the line 8--8 of Fig. 7; Big. 9 is a section on the line 9-9 of Fig. 7; Fig. 10 is a section on the line Ill-ll 01' Fig. '7; Fig. 11 is an enlarged plan of the protractor end of the drafting machine;

Fig. 12 is a section on the line l2-II of Fig. 11;

Fig. 13 is a section on the line |3-i3 of Fig. 11;

Fig. 14 is a section on the line ll-ll of Fig. 11;

Fig-15 is a section on the line l5-l5 of Figs. 1 1.6;

(CI. 33-79) The present invention relates to drafting ma- Fig. 16 is a section on the line "-48 and 15; v

Fig. 1"! is a section on the line "-41 of Fig. 'l; and

Fig. 18 is a view similarto Hg. 5 but showing a modified construction.

The drafting machineshown in the drawings is oiFigs.l..

the preferred embodiment of the present invention but it is to be understood that the invention can be otherwise. embodied, that changes and modifications may be made within the scope of the present invention, and that the particular drafting machine shown is merely illustrative of the invention.

angularly movable relative to each other, carry-- ing at one end thereof a protractor assembly and adapted at the other end for attachment to a. drafting board or table. In generahthe arm or parallel motion mechanism comprises two or more flexible compound bands encircling three or more grooved wheels of equal diameter held apart or in spaced relation by suitable struts. The preferred embodiment illustratedalso includes a counterpoise for balancing the weight of the arm, protractor assembly, etc., so that the same will remain stationary in any position to which it is moved irrespective of the inclination of the drawing board or table with which the same is used. In this respect the machine shown is admirably suited for use with vertical boards or tables or .those inclined at a substantial angle. But it will be understood that the counterpoise may be omitted as will be hereinafter apparent, if desired, and preferably so where the instrument is together by turnbuckl'es or takeups of suitable construction. The turnbuckles ,or takeups are i to be used with a horizontal or substantially hurlzontal board or table; as the omission of the cost of the machine panoramas ism provided for the purpose of adjusting the length ofthe cable bands with respect to the flat band I! and provide means for adjusting the distribubands It and I! may be replaced by a single cable band encircling the wheels twice .or arrangements may be employed if desired.-

The band A which encircles wheels II and 2| engages the samewithin' suitable band receiving grooves formed therein. The band may prefer 'tion of the load therebetween. The two cable other ably be attached to the wheel under some circum- ..stances to prevent sllpping but such a construction limits the movement of the p'arallelograms to 180' or less. The'upper wheel which in some respects forms a part of the anchor mechanism is fixed as by screws 24 to an anchor member 25 adapted to be attached or clamped to the edge of the drafting board or table 26 in any convenient manner as by the thumb screws 21. The wheel 2| is held in spaced relation to the wheel 20 for the purpose oi keeping the band A taut, etc.. by the strut designated generally by the reference character C, the lower end of which is provided with rollers." adapted to engage the periphery oi the wheel 2| within the band groove and against which the wheel 2| rolls in operation. The upper end or the strut C comprises a cross member I4 rotatably supported concentric with the wheel 20 by anti-friction bearings in the form of balls retained between outside races formed on the inside of an aperture extending through the wheel 20, and inside races "and 21 adjustably threaded on a stud 38 fixed to the cross member.

a The lower end of the strut C or the end thereof adjacent the elbow oi the arm, comprises two plates ll and II. held in predetermined spaced relation to each other and to the cross member by, side members I! and I3 preferably of channelsection and enclosing the flexible band AZ The ends or the 'side members A2 and H may be a connected to the cross member 24 and the plates ll and It convenient manner. As 'illustrated, the upper ends thereofare riveted to the member 34 and to short channel members I! and '40, which. inturn, are riveted to the member ll along with' theside members 42 and 4t, and the plates and. at the lower end of the strut are tothelwar e ds of the side members. platesfiland 4|, together with the side channelg'meinbelrs'gfl and 42, form a'box section 'Tx' withinfwhich'i member comprising a plurality of it and II" is slidably supported. The plates 1"" and II are secured together and held in predetermined spaced relation by -a plurality 01' members '2 vto'whichthey are suitably riveted,

carry-thee rollers supported by means o! I anti-friction-bearingsin the iorm oi balls 52 on pinsill riveted or otherwise securedthereto. As

stated; the rollers" engage ,within the upper band'groove' or the wheel 2| and retain the same in spaced relation to thewheel 2|.

. I'or the purpose of i'acilitatingassembly and "adjusting the tension oi! the band A the plates lland II which .ior'm a section telescoped within the" lower end oi the strutproper, are adapted to be moved within the box section formedby the plates ll and II and the side channel members l2 and 42, by a thumb screw 55 rotatably sup- "ported in a member 8 iixed to the plates I! and .II and threaded into a headed member 81 projecting through elongated slots rs in the plates II and II .and secured in aligned apertures in the "plates 4 0 and 4| by a screw it. As illustrated,

ooopera s projections and groovesformed in- 'theplates ,II and I0, and ll and SI, respectively,

- assist'in guiding theplatesil and II within the "4| jand .1 The lower edge of the plate ll is rounded or, concave to conform-with the wheel as shown in' Fig. 'l, and terminates short of the edgeofzithe wheel, but may project slightly over the wheel ii. desired. The lower edge of T 'theplate II is also concave or rounded and en'- gages withinagroove 2 formed in the wheel 2| below the upper band groove 23, which construction helps to maintain the axis or the wheel 2| normal to the longitudinal axis of the strut and assists in guiding the wheel during its rotation.

' Because of the additional stress to which the anchor strut C is subject in operation, the channel members 42 and 42 are braced midway between. their ends by a cross member 3 secured thereto in any convenient manner, and a tension member or rod 64. I The upper end of the rod it is bent at right angles and projects into a suitable aperture formed in the cross member ll, and the lower end. thereof projects through an aperture in the cross member it beyond which it is provided with an adjusting nut threaded thereon.

The wheel 2| which is approximately three times the thickness of the wheel 20, is common to both parallelograms, andtogether with the wheel 66 at the protractor end of the arm is encircled by the band B which engages within suitable grooves formed on the wheels 2| and I. The wheels 2| and are held in spaced relation by a strut D, the left hand end of which is sim-- ilar in'construction to thelower end 0! the strut C and comprises upper and lower plates II and ii secured as by rivets 12 to side members ll tension oi the band B, by a thumb screw 08 rotatably supported in a member ll fixed to the plates ll-and It; and threaded into a headed member, 2| projecting through slots 20 in theplates II and It and secured in aligned apertures in the plates II and" by a screw 21. The letthand'end oi the upper plate is concave. similar to the lower end 0! the plate II, and

oroiects into a groovell'i'ormed in the wheel 2| above the lower band groove, and the lower plate IQ is similarly shaped but terminates short of the wheel 2|. I

- The right hand ends or the side channel members II and I4 are secured 'as by rivets 22 to a rectanguiarly shaped member It provided with a downwardly projecting boss in the form of a tubular member or .bushing ll ilxedthereto in any convenient manner. The protractorassembly including wheel I of the parallelmotion mechanism is rotatably supported on the tubular member ll through the medium oi. the wheel I and anti-friction hearings in the iorm'of balls-2| retained between inside races I1 and II secured to the bushing II and outside races in the The wheel I. is provided with a downwardly and outwardly extending-flange Ill formed integrab.

1y therewith to which the protractor plate III I provided with suitable graduation is secured for limited rotational movement by screws "2 projecting through arcuate slots, III in the pro tractor plate and threaded into suitable tapped holes iii the flange ill. The screws "2 are provided with shoulders which engage the flange "I", leaving sumcient clearance to provide for free movement of the protractor plate. The promoved within the box section comprising the plates II and for the purpose of adjusting the tractor plate |0| is adapted to be clamped in any 7 l with a somewhat plate I01. In the adjusted position with reference to the flange I III by 'a thumb screw I04 threaded in a suitable tapped aperture in the protractor plate and. provided with a clamping member or washer I05. which engages the edge of the flange I and clamps the same therebetween and a portion of the protractor plate which-extends underneath the flange Hill.

The chuck plate III which, in the present instance, is in the formof an annular ring has'the "chuck arms I08 and II! which are formed integral similar member I I I, attached thereto by means of screws III. project through the chuck arms the member H0 and are threaded into the chuck The screws I I I and the member III), and the chuck plate, but

I the member their assembled 4 The upper surface of the chuck plate Ill engases the undersurface of and the two plates are together in any desired ously explained, by a vertical pin or shaft'IIi chuck arms and projecting through the bushing 84.

fixed to the The pin III is rotatable within the bushing 94 venient manner, and which retains the parts in relationship.

adapted to be clamped position bya floating clamp designated generally by the reference character E. The clamp E comprises two members 1 I and III adapted to extend over the edge of the protractor Psame together. The lower member I28 has a stud I22 fixed therein whichproiects through a suitable aperture in the and chuck platesfand clamp the upper member III above which it is provided with a I20 to the outside 0! the-stud Informs a fulcrum for the upper mem- The lower member-III has an arcuately shaped ridge or projection" I25 on the upper side thereof which engages in an annular. groove III :formed in the underside of the chuck plateand retains the clamp E in assembled position theregroove lfl also permits the with. The annular clamp E to be shifted toditferent positions about tional construction and chucked to the chuck arm' -g 2,049,302,suitablerorthe resent Mani- -bers I32 and! I33 attached to the flange I" and i the counterpoise,

the circumference of the protractor and chuck This construction is especially advan when the protractor, etc.,- are located plates. tageous underneath the arm. as is the case in the preferred construction illustrated, since'it permits a low, compact construction without "limiting the are through which the protractor and chuck plate canbe moved. p e rulers I and Ill .may be of any convenin any convenient manner, and the construction shown in United States 526,912 .'is,. which" has matured into Patent the chuck arm I"; respectively,"and provided facilitate the protraetor and rulers, etcm idea when the counterpoiseis not employed, as is often the case as previously pointed out. The

I" and I", and

present instance spacer members H2 are'interposed between the chuck arms of the chuck arms I", and III! and and is provided at itsuppe'r end with a hand grasp I It secured thereto in any conthe protractorplate III winged nut Iil for manual operation of theclamp. A screw I24 carried by the lower member pplicatlon Serial No:.

kill the flbracket J. V I tothe spring lllandis the that in which'the preferred embodiment of the counterpoise of the present invention comprises two enclosed springs operatively connected to the arm in such a manner as to balance the weight thereof and that of the protractor assembly, etc in any position to which the same is moved, The Weight of the anchor portion of the arm is balanced about its pivotal connection with the anchor by a tension upper edge of the board or table, operatively connected to the cross member ll through the medlum of a rod I31 pivotally connected to: a screw I" carried by a projection I38 formed on the cross member.- The screw I" is so positioned on the cross member 34 that it is on the opposite side of the axis about which the arm rotates from that of the spring when the anchor paralleL ogram is in a vertical position or at right angles to the upper edge of the board. In otherwords. the spring is attached to the anchor parallelo 'gram in such a manner that when the anchor parallelogram is in a vertical positionit does not exert any force thereon tending to rotate the same, since the force exerted by the spring is' directly across the-axis about which the arm ro rtates. As the upper parallelogram-f is moved in either direction from the vertical position,"ithe. spring I exertsa force thereon suillcient tosbalanee the weight thereof.

The spring III vision made for As shown. the spring Ifl is enclosed within a tubular member IIII and the right hand end thereof is connected to a tubularmembenlll threaded onto a long rod I42 projecting through the center of the member I. The rod I42 is rotatably supportedin a member I 43 secured to I and forming a closure for the end member Ill. The rod Ill projects through the member I" and to .the right thereofis provided with a knurled knob I formanual operation. From the foregoing it will be apparent that the tension of the spring II! can be readily adjusted by rotating the threaded rod I42 by means of is preferably enclosed and prothe knob I; The member III is prevented by a screw Ill 'a neat appearance but it gether or a member of different shape such as a channel member positioned with" the channel opening toward he"board-or the rear, mayfbe substituted therefor. g v x- 3 The weight .of the protractor portion'of the arm and that of the protractor. assembly; is balanced by a spring Iii,

chamber Ill, similar to thetubular member I,

'pivotally supported within a the tubular member In in 'a" manner similar to spring I151 is"secured within the tubular member "Ill, andu'jwill not be :de-

all.- The left hand end of the spring 1" is connected pin Ill ands screwtooneend of a cable I-lII which fatter making two turns about a helical or spiral camlllfl extends down along one side of the spring I 35 extending along the III 0 adjusting the tension thereof.

of the tubular I object of. the tubular x member is to enclose the springfland present. may be omitted altoenclosed within a tubular upper parallelogram underneath the side mem-. ber ll of the strut C to the elbow of the arm where it is attached to a wheel I" by ascrew I, after being wrapped partly thereabout. The earn 5 I" is rotatably supported on a stud I" in axial alignment with the bearingintheiormofballs iflretainedbetween the outside races formed in the aperture in the 5 cam through which the stud I" projects and 1 inside races ill and ill adjustahly threaded on the stud. The wheel III is secured to a plate or member I'll as by rivets I", which, in turn, are secured to the side members ll and ll of the The wheel it! blind to the strut D and turns in lmison therewith about the center of the wheel II asanaxis. Theleadofthe spiralcam iii is such that the eflective moment arm of the spring ill varies in such a manner that the weight of the protractor parallelogram is balanced, and can .bereadilydeterminedbyanyoneskilledin theart to meet the requirements of the particular problem-at hand. The cable I with the cam Iii forms a bell-crank connection at the anchor end of. the arm, from which it will be understood that the cam ill could be replaced by a conventional bell-crank lever, although the effective moment arm of the spring I" could not be so readily controlled. A conventional sheave could also be employed in place of the cam ill at the anchor end of them and the endjoi the cable I attached to the strut D either directly or through the medium of a cam similar to the cam' iii fwith varyin results. a One modification of the cam iii is illustrated inHgJS. Asshowninthisilgurethemaximum moment arm at which the spring it! operates occurs when the protractor parallelogram is horimntal and the anchor parallelogram vertical. The cam in this instance reference character iii. The cams shown are merely illustrative and, as previously stated, may be varied as desired, and the shape which gives the best results for the specific application at hand can be readily determined.

From the foregoing description of the preferred embodiment of the present invention it will be apparent that a novel draiting machine 'and counter-poise parallel motion mechanism or arm is light, strong, readily assembled and disassembled and gives a high degree of bility to the rulers. The side members of the struts through which the straight portions of the bands extend not only serve as guards to protect the draitsman from inJury in case a band should snap under the tension imposed in it, but as the bands are guarded by channel-shaped members not only is the application or removal of the hands facilitated but, what is of equal or greater importance, though guarded the straight portions between the wheels are accemible to the operator or draftsman. This is of considerable importance in enabling the drafts- -mah to test the tension of the band from time to time by pulling the band inwardly with a tool or with hisjlnger and then releasing it, and, by the tone resulting from the vibration. use its tension. This may be aptly termed "tuning" and is made possible that the nature of the guard for the band is such that the band is accessible and in this instance the guard ilanks the band only on its outer side, leaving its inner side free or uncovered for this purpose. Accordingly, the band may be said to b tunably guarded in the sense stud a, by an anti-friction.

isdesignatedbythe' therefor has been provided. The

onlybyreasonofthefact.

means or for the purpose described above. The counterpoise is compact, reliable and free from exposed springs, and on the whole the machine presents a very neat and pleasing appearance. while the preferred embodiment illustrated and de- 5 scribed incorporates a counterpoise, it will be readily apparent that the counterpoise could be omitted and such is within the contemplation of the present invention.

The preferred embodiment of the invention has been illustrated and described in detail, but I do not wish to be limited to the particular construction shown. which may be varied within the scope of this invention. It is my intention to cover all variations, adaptations, and uses thereof that come within the customary practice and skill of those skilled in the art to which the invention pertains, and I particularly point out and claim as my invention the following:

1. A drafting machine comprising a parallel motion arm, said parallel motion arm compris ing a plurality of wheels, a flexible compound band encircling said wheels, said compound band comprising an endless flat band and an endless cable band encircling said flat band, and a strut operatively connected to said wheels for maintaining said wheels in spaced relation, said strut comprising a plurality of side members of channel section partly enclosing said compound hand between the wheels.

2. A drafting machine comprising an anchor, a plurality of wheels, means for operatively connecting one of said wheels to said anchor, at flexible band encircling said wheels, a strut operatively connected to said wheels for maintaining said wheels in spaced relation, said strut comprising two spaced side members surrounding said band, a cross member connecting said'side members intermediate the ends thereof, a supporting member operatively connected to said anchor above the plane of said side members, and means for connecting said supporting member to said cross member.

3. A drafting machine comprising a parallel motion mechanism, said parallel motion mechanism comprising a plurality of wheels, a flexible band encircling said wheels, and a strut operatively connected to said wheels for maintaining the same in spaced relation, said strut comprising two sections telescoped together, one of said sections comprising side members partly enclosing said band and a plurality of spaced plates connected to said side members at one end thereof, the other ofsaid sections being slidably supported between said spaced plates.

4. A draiting machine comprising a parallel motion arm, said parallel motion arm comprising a plurality of wheels, a flexible band encircling said wheels, and a strut operatively connected to said wheels for maintaining the same in spaced relation, said strut comprising: two side members partly enclosing said band, a plurality of spaced plates. connected to said side members at one .end, a member slidably supported between said spaced plates, a plurality of rollers carried by said member and adapted to engage the periphery of one of said wheels, and means for moving said member relative to said plates.

5. In a drafting machine the combination of, an arm comprising sections angularly movable relative to each other, means for operatively connecting one end of said arm to a drafting table, resilient means adapted to be operatively connected at one end to the drafting table, means for operatively connecting the other end of said ragons resilient means to one section of said arm, a second resilient means adapted to be operatively connected at one end to the drafting table, and means for operatively connecting the other end of said second resilient means to another of the sections of said arm.

' 6. In a drafting machine the combinationoi, an arm comprising sections angularly movable lative to each other, means for operatively connecting one end of said arm to a drafting table, a plurality of tubular members adapted to be pivotally connected to the drafting table; tension springs positioned within said tubular members, means for operatively connecting one of said springs withone section of said am for balancing the same, and means for operatively con necting another of said springs with another oi? the sections of said arm for balancing the same.

7. In a drafting machine the combination of, an arm comprising two sections angularly movable relative to each other, an anchor operatively connected to one end of said arm for connecting the same to a drawing table, resilient means operatively connected to said board, and means for operatively connecting said resilient means to a section of said arm other than the section thereof adjacent the anchor, said last mentioned means comprising a member pivotally supported adjacent said anchor.

8. In a drafting machine the combination of, an arm comprising sections angularly movable relative to each other, an anchor operatively connected to one end of said arm for connecting the same to adrafting table, resilient means operatively connected to said table, and means for operatively connecting said resilient means to a section oi said arm other than'the section thereof adjacent the anchor, said last mentioned means comprising a bell crank connection adjacent said anchor. I r

9. In a drafting machine the combination of, an arm comprising sections angularly movable relative to each other, an anchor for operatively connecting one end of said arm to a drafting table, a plurality of tubular members adapted to be pivotally connected to the drafting table, tension springs positioned within said tubular members, means for operatively connecting one of said springs with one section of said arm for balancing the same, and means for operatively connecting another of said springs with another of the sections of said arm for balancing the same, said last mentioned means comprising a member rotatably connected to said anchor.

10. A drafting machine comprising a parallel motion arm composed of sections angularly mov-.

able relative to each other, means for operatively connecting one end of said arm to a drafting board, means for counterbalancing a section of said arm, said means extending generally along the upper edge of the drafting board in all operative positions of said am, and means for operatively connecting said means to one of said sections of said arm. a

11. A drafting machine comprising a parallel motion arm composed oiLsections angularly movable relative to each other, means for operatively connecting one end of saidarm to a drafting board, a spring for counterbalanclng a section of said arm, said spring extending generally along the upper edge of the board in all operative posi-' tions of said arm, and means for operatively connecting said spring to one of'said sections of said arm.

comprising a parallel sections angularly mov- 12. A drafting machine motion arm composed of able relative to each other, means for operatively connecting one end of said arm to a drafting board, resilient means for counterbalancing a section of said arm, said resilient means extending generally along the upper edge of the draftlng board in all operative positions of said arm, means'for operatively connecting said resilient means to one of said sections oi said arm, a second resilient means for counterbalancing another section of said arm, said means extending generally along the upper edge of the drafting board in all operative positions of said arm, and means i for operatively connecting said second resilient means with another of said sections of said arm. 13. A drafting machine comprising a parallel motion arm composed of sections angularly movable relative to each other, means for operatively connecting one end of said arm to a drafting board, counterpoise mechanism, a wheel rotatably supported adjacent the end of the arm adapted to be connected to the drawing board, a second wheel the diameter of which is equal to that of the iirst mentioned wheel connected to a section oi said arm other than the section adapted to be connected to the drawing board, and means for eonnecting said counterpoise mechanism with said section of said arm other than the section adapted to be connected to the drawing board including a flexible cable encircling said wheels.

1d. A drafting machine comprising a parallel motion arm composed of sections angularly movable relative to each other, each of said sections pair of wheels, bands encircling said wheels, struts for maintaining said wheels in spaced relation, an anchor for operatively connecting one end of said arm to a drafting board, counterpolse mechanism, a wheel rotatably supported coaxially with the wheel of said armadiacent said anchor, a second wheel connected to a section of said arm remote from the section thereof connected to the anchor concentric with a; wheel of said section, and means for operatively connecting said counterpoise mechanism with said section of said arm other than the section thereof connected to the anchor including a flexible cable extending about said wheels.

15. A drafting machine comprising a parallel motion arm composed of sections angularly movable relative to each other, each of said sections comprising a pair of wheels, bands encircling said wheels, struts operatively connected to said wheels for holding the same in spaced relation, anchor mechanism for operatively connecting one end of said arm to a drafting board, resilient means extending generally along the upper edge of the drafting board in all operative positions of said arm, means for operatively connecting said resilient means to the section of said arm connected to the anchor, resilient means extending generally along the upper edge of the drafting board in all operative positions of said arm, a wheel rotatably supported coaxially with the wheel of said arm at the anchor end thereof, a second wheel con nected to a' section of said arm other than the section thereof connected to the anchor, and means including a flexible band extending about said wheels for operatively connecting said second resilient means with other than the section anchor.

thereof connected to said onennnennrrrrn.

said section of said arm 

